1. Field of the Invention
The invention relates to a centrifugal slide grinder with a shell-like rotary receptacle bottom part and a stationary essentially cylindrical receptacle top part.
2. Description of the Prior Art
Centrifugal slide grinders are used for surface machining especially of smaller parts and workpieces which are moved together with the grinding wheels and optionally with a liquid process agent. As DE 44 28 817 C2 shows, a known centrifugal slide grinder has a top-opening, and shell-like bottom part which is rotary-driven around a vertical axis. Above the bottom part there is a stationary cylindrical receptacle top part which rests with its lower edge on the upper edge of the bottom part with the interposition of a seal. When the bottom part is caused to rotate the workpieces to be machined are forced radially to the outside in the bottom part until they meet the inner wall of the stationary receptacle top part which causes a braking action to be applied to the work pieces. Radially peripheral workpiece motion which causes intensive grinding arises by workpieces following from upstream.
The transition area between the upper edge of the turning bottom part and the lower edge of the stationary receptacle top part is very susceptible to wear. Attempts have therefore been made to make the seal which acts between these two parts as a slip ring seal, the slip ring located on the bottom part and/or on the receptacle top part consisting of ceramic. In this way the wear which occurs in the seal can be reduced, however ceramic rings of a larger diameter are very expensive and the additional problem arises that the diameter of the ceramic rings and thus the diameter of the receptacle top part is limited by production technology to a maximum roughly 50 cm, so that a centrifugal slide grinder of this type in its volume and also in its performance is subject to serious limitations. Attempts have been made to form a ceramic ring from several ceramic ring segments, in doing so however problems occurred with regard to sealing.
In DE-P9 44 28 817 the seal which acts between the two parts is formed by a hardened steel ring on the bottom part and a felt ring on the receptacle upper part. By means of screws the desired contact pressure is established between the soft ring seal of felt or nonwoven material and the steel ring. If the felt ring is worn for example by the working of fine grinding media into the felt, on the contact surface between the two annular seals a gap forms which can no longer be equalized by the felt seal. This and the wear due to friction on the contact surfaces between the receptacle upper and bottom part then leads to the fact that extremely small parts can no longer be machined.
In known centrifugal slide grinders with slip ring seals in which the parts of the receptacle bottom part and top part which form the seals are pressed elastically against one another, lubrication takes place by means of a lubricating fluid which can penetrate to the interior of the receptacle part.
In many grinding processes it is desirable or necessary to ensure absolute dryness within the grinder, which is not the case in known grinders which operate with a fluid.